License Plate Guitar

In MAKE Volume 04, Ed Vogel showed us how to make a DIY guitar out of a cigar box and junk from the hardware store, and electrify it with a cheap piezoelectric pickup. In Volume 21, Mark Frauenfelder gussied it up with a traditional high-quality neck, frets, and tuning machines. In this project we’re going to turn it up to 11 with the help of an old license plate and a few components from RadioShack.

A popular DIY resonator guitar, the License Plate Guitar is easy to make. You’ll wind your own electromagnetic pickup and mount it on a homemade soundbox made with an old automobile license plate for the metal resonator top. Then add a potentiometer and volume knob and get ready to rock that classic electric blues sound.

Step #3: Clamp and glue the box.

Place one of the long box sides into your corner clamps but keep the clamps loose so they can be easily adjusted. Apply a liberal amount of glue to the angled ends of the board.

Place the 2 short box sides into the clamps and adjust the clamps until all the 2 corners are perfectly aligned to 90° angles. Tighten the clamps and leave these 2 joints to dry for at least 6 hours; 24 is better.

When the first 2 joints are dry, apply glue to the remaining 2 joints and clamp in the final board. Leave these again to dry for at least 6 hours.

Step #6: Prepare the neck.

The fret spacing on the neck is designed for a 25" scale length between the nut and the bridge. The distance from the edge of the guitar body (where you'll attach the neck) to the bridge (which you'll attach to the license plate) should be around 9". So you'll need to cut down the neck to about 16".

Starting where the headstock meets the neck, measure 16" down the neck and make a mark for cutting.

Clamp the neck in your miter box and cut it squarely at your mark. Save the extra scrap piece for use later.

Step #7: Prepare the headstock.

The headstock can be an opportunity to really customize the look of your guitar. We decided to keep ours simple to match the straight lines of our guitar body, so we just trimmed the headstock down, making it about 1/4" wider than the neck on each side.

Next mark the spacing for your tuning machines on the headstock. You want a grid of 4 holes centered in the headstock as shown here, each hole 1/2" from the edges of the headstock and with 2" between each row.

After marking your grid, drill the holes with a 1/4" drill bit.

TIP: To prevent chip-outs, drill the holes from the top of the neck, and put a sacrificial backing board under the bottom of the neck.

Step #8: Install the tuning machines.

Our tuning machines came with metal grommets that help them operate smoothly in your guitar. Place those grommets through the holes in the front of the headstock.

Flip the neck over, test-fit the tuning machines through the headstock, and mark the location of each of the mounting screw holes.

NOTE: If your tuning machines have an exposed gear, it should be oriented downward toward the neck, not upward toward the top of the headstock. If you install them upside down, they can't maintain tension.

Step #9: Add the nut.

At the point just below the headstock where the fretboard flattens out, place your nut across the neck running perpendicular. Use a pencil to mark both edges of the nut.

Between your marks, use your coping saw or other handsaw to cut a groove 1/8" deep into the neck. Do this multiple times to remove most of the material between the marks. Then use a knife to clean the remaining wood from the channel, and use sandpaper to smooth it.

Once your channel is cut enough to fit the nut into place, trim your nut to the width of your neck and glue it into place in the channel.

Step #10: Attach the neck.

Drill a pilot hole in the center of the end of your neck, using a bit slightly smaller than your 1-1/2" wood screws.

Measure the thickness of the neck and of the license plate. Divide the neck thickness in half and subtract the thickness of the license plate. Measure down from the edge of one short sides of your body box the same length you just calculated and drill another pilot hole centered in the board.

Now use wood glue and a 1-1/2" wood screw to attach the neck to the body. Make sure it's perfectly squared up and not twisted. Placing a small amount of glue between the neck and body will help prevent the joint from loosening in the future.

Step #13: Secure the license plate.

From the 1.5"×1.5" hardwood stock, cut 2 lengths that are as long as the walls of the guitar body are deep (~3 inches). These can be cut in the miter box to ensure 90° flat cuts.

Center the license plate on top of the body box and mark the locations of the plate's 2 existing screw holes that are on the opposite end from the pickup hole.

Place glue on one side of each of the 2 blocks that you just cut and clamp them inside the box as shown, so they're centered on your screw hole markings. Leave the glue to dry for at least 6 hours.

Finally, coat the top surfaces of the frame with glue and clamp the license plate on to secure it. Add clamps as needed to ensure that your license plate is making good contact on all edges, the whole way around. Again, let the glue dry at least 6 hours.

Step #14: Build a single-coil pickup.

An electric guitar uses an electromagnetic device known as a pickup to capture the vibration of the strings and convert it into a signal that's sent to the amplifier. (We based our pickup design on this great tutorial on Instructables.) It's basically a coil of wire and some magnets; vibration creates fluctuations in the magnetic field, which are picked up and converted to a small electrical current.

Step #15: Cut the pickup bobbin.

Measure the hole you cut in the license plate, and design a rectangle that's slightly larger than the hole. This will be the bobbin's top plate. It can be drawn by hand or created digitally using an application such as Inkscape or Adobe Illustrator. Design a second template that's approximately twice as tall, for the bobbin's bottom plate.

Mark a pattern of 4 holes evenly spaced 1/2" apart in the center of the top template. Copy this hole pattern to the lower half of the bottom template, then add 2 more holes centered near the upper edge of the bottom template.

Tape the templates to a piece of 1/4" plywood and cut them out with your coping saw or jigsaw. Use sandpaper to clean up the edges.

Step #18: Wind the pickup.

Insert the magnet wire into one of the 2 wire mounting holes in the bottom of your pickup bobbin. Wrap it through the hole and around the outer edge a couple of times to secure it.

Wrap the wire neatly around the entire group of 4 screws at the center of your bobbin (not between the screws). Keep your wrapping even and consistent, starting at the bottom and building layers to the top. Continue wrapping all of the wire from the spool onto the pickup.

When you're near the end of the wire, loop it through the remaining mounting hole multiple times to secure it in place.

Step #19: Add the magnets.

Place one rare-earth magnet on top of each screw, at the end with the nut. These should stay in place on their own, but to ensure they don't come loose during any particularly rocking jam session in the future, you can attach them with a drop of super glue.

Step #20: Wire the pickup.

Magnet wire is coated with a thin film to insulate it; you need to strip this coating off the wire ends before you can solder them. It can usually be easily burned off with your soldering iron; you can also try to scrape it off using a sharp knife, razor blade, or sandpaper.

Solder one end of the cable to the 2 magnet wire ends coming out of your pickup.

Step #23: Drill holes for the pot and jack.

Decide where you'd like to place your audio jack and volume control on the face of the license plate. Mark those locations and drill holes in the license plate, using a drill bit slightly larger than the component you're going to mount.

Step #26: Place the bridge.

Measure and mark the license plate 25" down from the nut. Place the bridge onto the license plate, making sure it's squarely aligned with the neck and fretboard, and glue it in place. Let the glue dry.

Step #27: String your guitar.

Thread the 4 strings through the string holder, starting with the thickest string and ending with the thinnest.

Run the strings over the bridge and then over the nut and finally into the hole of the tuning machine. As shown in the second photo here, the thickest string should mount into the lower left tuning machine, the next into the top left, followed by the top right, and finally the bottom right.

When all the strings are in place, tighten down the tuning machines evenly but without applying too much tension.

Step #28: Test it and close it up.

Plug your License Plate Guitar into your amp, switch on the amp, and strum the strings. You should hear your new electric guitar!

If it's working properly, it's time to close it up. (If not, unplug everything, check your connections, and try again.) Test-fit the plywood back on the guitar body and drill 4 pilot holes through the back into the body walls.

Secure the back to the body with four 3/4" wood screws.

Step #29: Tuning and playing.

There are numerous free apps for iOS, Android, Windows, and Mac that will allow you to tune the guitar. Choose the scale you would like it tuned for and then tune each string to the proper pitch. Now plug your new guitar into your amp and rock on!

A popular tuning for small guitars like this is called open G tuning. As Mark wrote in Volume 21, "Many of the original blues guitar players used open G, and it's a favorite with Keith Richards of the Rolling Stones."

For more tips and lessons on playing your License Plate Guitar, look for Keni Lee Burgess and Shane Speal at Cigar Box Nation or on YouTube.